Most indoor spaces that are designed for human activity include artificial electric illumination to a level of at least 30 footcandles, with most work areas illuminated to 60 footcandles or more. This level of illumination is quite sufficient for all modern film and video cameras, which can record an image with 10 footcandles or less. Video camera manufacturers often encourage users to create video programs using nothing more than the available illumination. The video images thus created are usually quite unacceptable due to the fact that the available illumination is almost always in the form of ceiling or overhead lights. This type of illumination creates shadows on the face, dark eye sockets and black necks, and accentuates facial wrinkles. Furthermore, the forehead, nose and shoulders are significantly overbright and appear to be glowing. Thus, the available overhead light is often unacceptable for foreground subjects.
The use of built-in light meters in automatic cameras is well known. The iris of the camera is adjusted in accordance with the output of the light meter to compensate for factors such as film speed (camera sensitivity), shutter speed, and scene illumination. However, the shadowing problem described above is not alleviated.
A reflective light metering device has been incorporated into lights for home video cameras. The metering device determines the amount of light reflected off the subject in order to increase the output of the camera's onboard light in low light and to decrease the output in bright light. This is usually accomplished by a variable resistance in series with the light, which increases or decreases the voltage applied to the light bulb.
U.S. Pat. No. 4,666,280, issued May 19, 1987 to Miyawaki et al, discloses a flash unit wherein the degree of concentration of flash lighting is varied responsive to detection of a backlight situation. The concentration of the flash unit light is increased when the backlighting increases so as to match foreground subject illumination with the background.
U.S. Pat. No. 4,959,755, issued Sep. 25, 1990 to Hochstein, discloses a video camera including a light sensor for sensing ambient light and reflected radiant light from a scene. The lamp intensity is lowered when the ambient light level increases. This patent discusses U.S. Pat. No. 4,368,406 in which a light control includes an ambient light sensor wherein the light is raised and lowered in concert with the ambient light. The light control is for use with a lighted control panel for a vehicle or the like.
U.S. Pat. No. 4,587,457, issued May 6, 1986 to Lind, discloses a multiple-intensity controller with variable impedance which is responsive to ambient light levels and may be used to increase the output intensity with increases in ambient light levels. Use with a camera is not disclosed.
U.S. Pat. No. 3,962,600, issued Jun. 8, 1976 to Pittman, discloses a control circuit wherein ambient light is sensed and the light of a clock is controlled. The clock light is increased in intensity in concert with increases in the ambient light.
It is a general object of the present invention to provide an improved photographic lighting system.
It is another object of the present invention to provide a photographic lighting system wherein shadowing is alleviated.
It is a further object of the present invention to provide a photographic lighting system wherein fill light intensity is increased in concert with incident light so as to alleviate shadowing.
It is yet another object of the present invention to provide a photographic lighting system wherein fill light intensity is based on the intensity of incident light on a subject to be photographed.